1. Technical Field
This invention relates to food products utilized in instant cooking having the ability to be stored for long periods without need of high temperature sterilization. Specifically, this invention relates to oil impregnated food products which retain the material color and flavor of their raw ingredients.
2. Background Art
Methods of producing keepable sterilized and sealed foods such as canning, bottling and retorting have been utilized broadly over the last 150 years and have been applied to fruits, vegetables, meat, marine products, and cooked products and so on as safety foods. They can be distributed at room temperature because microbiological resistance and sterility makes it possible to store them for a long period of time at room temperatures.
In sterilized and sealed foods such as the above mentioned, keepability is definitely influenced by whether or not the sterilization after sealing is perfect. Generally, the means for sterilization utilized in the industrial field is wet heating sterilization by vapor. It is used for the purpose of establishing sanitary conditions by making extinct all toxic and nontoxic microorganisms that are generatable in foods under storage without cooling or generatable while under distribution.
Suitable heating conditions for the above mentioned are varied by the pH and water activity of the products, heat resistance of microorganisms, packaging size and the physical properties of the foods. Particularly, pH and water activity are influential elements for microorganisms generation. Acid foods having a pH of less than 4.6 such as canned fruits are low temperature sterilized at temperatures less than 100.degree. C., and low acid foods having pH in a range of 4.6 to 8.0 such as canned marine products are high temperature sterilized at temperatures more than 100.degree. C. It is well known that the generation of microorganisms which can decompose canned foods are commanded by water activity at a border value of 0.93 or 0.4.
According to the Food Sanitation Act of Japan, it is necessary to apply heat sterilization of at least 120.degree. C. for 4 min. (this is necessary for die out botulism bacillus) when producing food products having a pH of more than 5.6 and water activity of more than 0.4. Most canned foods are wet, low acid foods having water activity of more than 0.94 with pH values in a range of 4.6 to 8.0. Therefore, they need heat sterilization as described above. However, when using perishable materials characterized by fresh flavor and vivid color, heat sterilization causes several problems. That is to say, denaturation of protein and decomposition of pigment occur as a result of heat sterilization; this and other influences damage the raw material's precious flavor and color. Therefore, supplying these kinds of food products in canned form under room temperatures is very difficult.
Japanese Patent First Publication No. 59-34874 discloses a method for producing food products by adding ethylalcohol to pastes after cooking. Japanese Patent First Publication No. 61-31930 and No. 63-279770 disclose methods for producing sauce or suspension by cooling suddenly and kneading a mixture of molten oils by heating and an added emulsifying agent. U.S. Pat. No. 4,746,524 discloses a method for producing food products by adjusting the pH while also adjusting the water activity of the ingredients of the food products. U.S. Pat. No. 3,769,042 discloses a method for making food products by immersing solid pieces in a liquid phase gravy or sauce comprising an aqueous solution of stabilizing solutes to infuse a portion of the solutes into the solids phase to the extent of reducing water activity of the solids phase to a level ranging from about 0.6 to 0.9 and forming a surrounding liquid phase gravy to have residual stabilizing solutes such that water activity of the liquid phase differs from the water activity of the solids phase by less than 0.1.
Though food products produced by the above mentioned methods have resistance to microorganisms and relative long storage ability and retaining materials' flavor thereof, further storage ability at room temperatures and restoration ability are needed. Additionally, food products for instant cooking by mixing thereof with materials such as boiled noodles and rice using oil for cooking is needed.
It is well known that lowering the water activity of products inhibits generation of microorganisms as previously mentioned for long storage. Products that are merely dried are different from the raw materials before drying in flavor, color, taste and so on. It is also well known that storage methods such as salting, pickling, miso pickling, sweetening and so on greatly change the material's taste. Therefore, these methods of raising osmotic pressure can be applied for only certain types of food products.
In light of the above-mentioned background, it is the object of this invention to provide new food products for instant cooking which retain the raw ingredient's natural flavor and color and methods of producing same.
It is another object of this invention to provide new food products which can be stored for long periods of time at room temperatures and methods of producing same.
It is a further object of this invention to provide new food products without sterilizing at high temperatures and methods of producing same.